1. Field of the Invention
Embodiments of the present invention generally relate to a completion operation. More particularly, the present invention relates to an apparatus and a method for generating data representative of a condition of a tubular.
2. Description of the Related Art
The safe and continuous operation of hydrocarbon wellbores and pipeline networks is essential to the operators and users of such networks. Accordingly, such wellbores and pipeline networks are cleaned and inspected at regular intervals to ensure their operational integrity.
The conventional approach to inspection of operating pipelines is for the tubular string to be precleaned several times using a “dumb” pig. The dumb pig, without any on-board intelligence, typically operates to scrape and remove debris such as wax, scale, sand, and other foreign matter from the tubular. In a newly formed pipeline with a new tubular string, the step of precleaning may not be required. In either case, a detailed inspection is subsequently performed by an inspection pig or caliper tool, which makes detailed measurements of the tubular string to determine the internal condition of the tubular. The inspection pig is typically equipped with technologies of varying sophistication. For example, the inspection pig may include a mechanism for measuring an interior surface of the tubular string.
A typical inspection pig includes multiple caliper arm assemblies for sensing changes in the contour of an interior surface of the pipeline. The caliper arm assemblies are generally interconnected to each other through various mechanical linkages. In addition, the caliper arm assemblies are typically connected to a single electronic sensor for receiving a signal from the caliper arm assemblies in response to the change in the contour of the interior surface of the pipeline. An example of an inspection pig is disclosed in U.S. Pat. No. 4,953,412, which is incorporated herein by reference in its entirety. The inspection pig disclosed in the '412 patent includes multiple finger mechanisms or caliper arms attached to a flow cup. The multiple finger mechanisms are interconnected to each other through an integrator plate assembly and other mechanical linkages. As a result, the movement of one of the finger mechanisms causes each of the other finger mechanisms to be affected. For instance, as the inspection pig travels though a pipeline, the external peripheral edge of the cup conforms to the interior configuration of the pipeline and as it changes contour this change is transmitted through the fingers and mechanical linkages to an integrator plate and subsequently to a single electronic sensor.
Although the arrangement of the typical inspection pig is functional, there are several shortcomings. One shortcoming is that the mechanical linkage that interconnects the caliper arm assemblies is bulky and therefore limits the number of caliper arm assemblies employed in the inspection pig, thus reducing the accuracy of the inspection operation by limiting the contact points between the inspection pig and the interior of the pipeline. Another shortcoming is that the caliper arm assemblies are interconnected through various mechanical linkages to a single electronic sensor. This arrangement limits the ability of the inspection pig to respond to multiple, simultaneous changes in the contour of the pipeline because the single sensor receives one signal at a time. As a result, the accuracy of the inspection operation is reduced.
There is a need therefore, for an inspection pig having a compact caliper arm assembly arrangement. There is yet a further need for an inspection pig having an independent sensor for each caliper arm assembly. Additionally, there is a further need for an improved inspection pig.